linux-kernel - Re: [PATCH v5 5/6] drm: sun4i: Add support for enabling DDC I2C bus to sun8i_dw

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Date:   Tue, 21 May 2019 13:46:11 +0200
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     megous@...ous.com
Cc:     linux-sunxi@...glegroups.com, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Mark Rutland <mark.rutland@....com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v5 5/6] drm: sun4i: Add support for enabling DDC I2C bus
 to sun8i_dw_hdmi glue

Hi,

On Tue, May 21, 2019 at 01:50:08AM +0200, megous@...ous.com wrote:
> From: Ondrej Jirman <megous@...ous.com>
>
> Orange Pi 3 board requires enabling a voltage shifting circuit via GPIO
> for the DDC bus to be usable.
>
> Add support for hdmi-connector node's optional ddc-en-gpios property to
> support this use case.
>
> Signed-off-by: Ondrej Jirman <megous@...ous.com>
> ---
>  drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c | 55 +++++++++++++++++++++++++--
>  drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h |  3 ++
>  2 files changed, 55 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
> index 39d8509d96a0..59b81ba02d96 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
> +++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
> @@ -98,6 +98,30 @@ static u32 sun8i_dw_hdmi_find_possible_crtcs(struct drm_device *drm,
>  	return crtcs;
>  }
>
> +static int sun8i_dw_hdmi_find_connector_pdev(struct device *dev,
> +					     struct platform_device **pdev_out)
> +{
> +	struct platform_device *pdev;
> +	struct device_node *remote;
> +
> +	remote = of_graph_get_remote_node(dev->of_node, 1, -1);
> +	if (!remote)
> +		return -ENODEV;
> +
> +	if (!of_device_is_compatible(remote, "hdmi-connector")) {
> +		of_node_put(remote);
> +		return -ENODEV;
> +	}
> +
> +	pdev = of_find_device_by_node(remote);
> +	of_node_put(remote);
> +	if (!pdev)
> +		return -ENODEV;
> +
> +	*pdev_out = pdev;
> +	return 0;
> +}
> +
>  static int sun8i_dw_hdmi_bind(struct device *dev, struct device *master,
>  			      void *data)
>  {
> @@ -151,16 +175,29 @@ static int sun8i_dw_hdmi_bind(struct device *dev, struct device *master,
>  		return PTR_ERR(hdmi->regulator);
>  	}
>
> +	ret = sun8i_dw_hdmi_find_connector_pdev(dev, &hdmi->connector_pdev);
> +	if (!ret) {
> +		hdmi->ddc_en = gpiod_get_optional(&hdmi->connector_pdev->dev,
> +						  "ddc-en", GPIOD_OUT_HIGH);
> +		if (IS_ERR(hdmi->ddc_en)) {
> +			platform_device_put(hdmi->connector_pdev);
> +			dev_err(dev, "Couldn't get ddc-en gpio\n");
> +			return PTR_ERR(hdmi->ddc_en);
> +		}
> +	}
> +
>  	ret = regulator_enable(hdmi->regulator);
>  	if (ret) {
>  		dev_err(dev, "Failed to enable regulator\n");
> -		return ret;
> +		goto err_unref_ddc_en;
>  	}
>
> +	gpiod_set_value(hdmi->ddc_en, 1);
> +

Do you really need this to be done all the time? I'm guessing you
would only need this when running .get_modes, right?

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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